How Mo.co used AI to test the player experience

• Supercell data scientist Markus Ojala discussed using bots to test games before launch.
• He spoke at PGC Helsinki 2025.

Balancing player experience before a game launches can be done with AI bots, trained to test a title and its content, features, and gear.

Through "reinforcement learning", thousands of bots can test a game on a large scale, encountering exploits or unintended strategies along the way, even if "imitation learning" from actual players isn’t yet possible.

"The beauty of reinforcement learning is you don’t need any rules for the players," said Supercell data scientist Markus Ojala, presenting learnings from Mo.co at PGC Helsinki 2025.

"Bots are basically randomly doing something, and if they do the right thing, for example killing a boss, they can be refined to say ‘do more of this’."

Testing with tech

Supercell’s portal-hopping dungeon explorer Mo.co went global this summer after a period of semi-global availability. Starting in March, the game was playable everywhere but on an invite-only basis, requiring an existing user to grant access to someone new. This gave Supercell further opportunity to test it in players’ hands before the full global release.

Ojala shared that prior to this, when bots were testing the game, they might have gravitated towards particular items - signalling to developers that these needed recalibrating because they were overpowered.

"We don’t use the bots in Mo.co for actual opponents. We use them just when we are developing the game and introducing new items," he clarified.

"During the Mo.co development cycle, developers were introducing new ideas maybe every one or two weeks and then our bot developers basically trained a new model and then saw how the bots started utilising all of them."

Ojala proceeded to explain Mo.co’s AI simulator and training framework used to test the player experience before release.

Pocket Gamer Connects London 2026 is taking place on January 19th and 20th with its AI Advances track highlighting the tech’s latest creative potential.